17 September 2012 Seismic analysis of the LSST telescope
Author Affiliations +
Abstract
The Large Synoptic Survey Telescope (LSST) will be located on the seismically active Chilean mountain of Cerro Pachón. The accelerations resulting from seismic events produce the most demanding load cases the telescope and its components must withstand. Seismic ground accelerations were applied to a comprehensive finite element analysis (FEA) model which included the telescope, its pier and the mountain top. Response accelerations for specific critical components (camera and secondary mirror assembly) on the telescope were determined by applying seismic accelerations in the form of Power Spectral Densities (PSD) to the FEA model. The PSDs were chosen based on the components design lives. Survival level accelerations were determined utilizing PSDs for seismic events with return periods 10 times the telescope's design life which is equivalent to a 10% chance of occurring over the lifetime. Since the telescope has a design life of 30 years it was analyzed for a return period of 300 years. Operational level seismic accelerations were determined using return periods of 5 times the lifetimes. Since the seismic accelerations provided by the Chilean design codes were provided in the form of Peak Spectral Accelerations (PSA), a method to convert between the two forms was developed. The accelerations are also affected by damping level. The LSST incorporates added damping to meets its rapid slew and settle requirements. This added damping also reduces the components' seismic accelerations. The analysis was repeated for the telescope horizon and zenith pointing. Closed form solutions were utilized to verify the results.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Douglas R. Neill, "Seismic analysis of the LSST telescope", Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84440T (17 September 2012); doi: 10.1117/12.926258; https://doi.org/10.1117/12.926258
PROCEEDINGS
15 PAGES


SHARE
RELATED CONTENT

Concept design for seismic upgrade of Keck telescopes
Proceedings of SPIE (August 08 2016)
LSST telescope mount concept
Proceedings of SPIE (June 23 2006)
Seismic design accelerations for the LSST telescope
Proceedings of SPIE (September 17 2012)
LSST Telescope mount and pier design overview
Proceedings of SPIE (July 28 2010)
Discovery Channel Telescope: progress and status
Proceedings of SPIE (June 27 2006)

Back to Top